Vigorous research efforts are being made recently in the field of a mobile phone-purpose camera module, a digital still camera (DSC), a camcorder, and a PC camera (an imaging device attached to a person computer) all connected with an image pickup system. One of the most important components for a camera module related to the image pickup system to obtain an image is an imaging lens that produces an image.
Recently, an optical lens system is constructed by using 3 or 4 pieces of lenses for realization of compactness and low cost.
For example, one known art in the related field, Korea Laid-Open Patent No. 2005-0014108 has attempted to construct a compact optical system using 4 pieces of lenses adequate enough to be mounted on a small sized information terminal.
However, although the 4-piece lens system may be advantageous in terms of price, but in some cases, an image module of the above-mentioned structure fails to show satisfactory optical properties or aberration properties, and thus a high resolution imaging lens having a power structure is required.